CVD growth of Ge Films on Graded Si_(1-x)Ge_x: C Buffers

摘要

Ge films have been deposited on Si (100) substrates with graded Si_(1-x)Ge_x:C buffers by chemical vapor deposition (CVD) method. Based on the Auger electron spectroscopy result, a growth model for the buffers has been proposed, in which the buffers are thought to be composed of two layers. One is the Si_(1-x)Ge_x:C epilayer due to the reaction of GeH_4, C_2H_4 and Si atoms diffusing up from the substrate, and the other is the Si_(1-x)Ge_x layer due to the reaction of Si and Ge atoms diffusing down from the Si_(1-x)Ge_x:C epilayer. The energy dispersive spectroscopy result indicates that Ge atoms diffuse further when the growth temperature is higher, demonstrating the growth model indirectly. With the graded buffers, epitaxial Ge films show the perfect crystalline quality, and the excellent transport property with the electron mobility approaching that of bulk Ge materials at the same doping level.